This invention relates to a resilient foundation support structure or assembly for items of furniture. In one particular application, the invention is directed to box spring assemblies used for supporting mattresses. However, the present invention is not limited to foundation supports for mattresses but includes any other item of furniture in which such a support structure is required specifically, chairs, sofas and other types of upholstered furniture.
The standard prior art box spring comprises a wooden rectangular frame, the longer sides of which are connected by a plurality of transverse wooden slats or members, a plurality of individually acting coiled springs mounted in a spaced relationship along the frame and the slats, and a supporting web of light wire interconnecting top portions of each individual coiled spring. The entire upper surface and sides of this structure are covered with cloth or other suitable sheet material. Other common prior art structures involved the substitution of tortion bars in place of the coiled springs. However, in both of these prior art structures, the individual supporting units act independently of one another.
In order to obtain the appropriate desired firmness in such assemblies, it is frequently necessary to incorporate along the perimeter of the frame additional springs which act as stabilizers or to use a very heavy (low gauge) wire to form the springs. These stabilizers provide edge support along the frame. In addition to the above structural limitations in the prior art the box spring assembly requires a great deal of manual labor in its construction. Each individual spring has to be hand positioned onto the frame or slats and secured thereto and then attached to the top web or grid structure. Naturally the amount of hand labor involved in this assembly process greatly increases the cost of the prior art box springs and makes assembly time quite lengthy. In addition, in the prior art box springs it was impossible to optimize both durability and firmness. If the coil springs are tensioned to provide a high degree of firmness, the life or durability is reduced and if the durability is increased, the tensioning of the spring became so slight that the firmness is unsatisfactory and additional springs or stabilizers have to be added to the box spring unit.